Couplings for linking conduits are particularly suitable for the construction of movable arm systems, more particularly systems where fluids, such as air under vacuum, are convoyed by the conduits hanging above the ground. In such systems, the couplings are a key element because the versatility of the systems depends upon the adjustability of the arms and the maximum weight that can be put at their free end.
The main drawback of the couplings of the prior art systems is that they are difficult to adjust and that fine adjustments are often altered after a short period of time, thereby making the systems unstable and tending to fall. Additionally, the length of the conduits cannot be changed because the couplings are designed to be used under specific load conditions. Counterbalance is usually provided inside the conduits by means of springs extending along the conduits and they are difficult to replace.
In some other couplings, the link between the interior of the conduits is a flexible tube, which usually has a large diameter that cannot withstand high thermic loads or high vacuum pressure.